1. Field of the Invention
The present invention relates to a method of creating charged beam drawing data used for a charged beam drawing apparatus to draw a pattern on a sample using a charged beam, a charged beam drawing method, a charged beam drawing apparatus and a semiconductor device manufacturing method.
2. Description of the Related Art
In manufacturing of LSI currently, there is an increasing demand for high precision of pattern transferring and processing dimensions for high integration of wires and devices. To respond to such a demand, recently, an electron beam drawing apparatus has been used for drawing a fine pattern on a sample such as a semiconductor wafer or a mask substrate.
Design data of a device pattern to be drawn on a sample is normally converted beforehand into drawing data corresponding to a drawing apparatus. The drawing data is recorded (stored) into a storage device or the like attached to the drawing apparatus.
The step for converting the design data into the drawing data includes a step of decomposing the device pattern into relatively simple patterns (for example, rectangular patterns), and a step of dividing the design pattern into mesh fields corresponding to the deflection width of an electron beam of the drawing apparatus.
In the pattern drawing by an electron beam drawing apparatus, an electron beam where an electron generated from an electron source is accelerated is formed through a plurality of variable apertures with reference to the drawing data, and this formed electron beam is deflected by two stages or more of deflectors, and focused onto a sample on a movable stage by an electromagnetic lens, thereby a pattern is drawn (Japanese Patent Nos. 3085918, 3125724, and 3168996).
FIG. 14 is a view schematically showing an example of the field division of design data that is performed in electron beam drawing. In FIG. 14, a subfield is divided into 4×4.
In FIG. 14, reference numeral 91 (square shown by a thick solid line) shows a subfield, 92 to 94 (patterns shown by diagonal lines) show design data corresponding to drawing data of relatively large dimensions (for example, 130 nm L&S or pad electrode), 95 to 97 (patterns shown by stripes) show design data corresponding to drawing data of relatively fine dimensions (for example, 60 nm L&S).
At the center of a drawing field, the deflection angle by a corresponding deflector is zero. At the portion that is more apart from the center of the field, the deflection angle of an electron beam becomes larger. When the deflection angle of the electron beam is large, blurring of the beam becomes relatively large owing to aberration of the electromagnetic lens and the like, and as a consequence, the resolution of the pattern drawing becomes lower than that at the center of the field.
FIG. 15 shows results (SEM photos) of an evaluation by an SEM on resist pattern drawn by a conventional drawing method by use of the design data of FIG. 14, and obtained after a developing process and the like.
From FIG. 15, it is known that the resolution of the fine pattern that is near the field center entangled by a dotted line is relatively preferable. Further, it is known that there is not a significant problem in the resolution even in the relatively large pattern at the end of the field outside of the dotted line. However, it is known that, in the fine pattern at the edge of the field, the deterioration of the resolution is conspicuous, and it is extremely difficult to resolve the fine pattern.
As a method for solving this problem, and for resolving fine patterns in the entire drawing area, there is known a method in which the drawing field is set small, and the electron beam deflection width is made small, thereby drawing is performed. However, in the above method, the number of drawing fields increases. Consequently, there occurs a problem that it requires longer drawing time than the above conventional drawing method, and the throughput is decreased.